The present invention relates to an optical unit and a projection-type displaying apparatus using the optical unit therein, for conducting image display by projecting an image from a image display element(s), enlargedly, upon a screen.
In Japanese Patent Laying-Open No. Hei 5-134213 (1993), for example, is already disclosed a technology for projecting an image on a screen into the direction inclined or oblique to the screen, while shifting the projection screen into the direction perpendicular to an optical axis of a projection system, with using an additional optic system, being disposed by inclining by a predetermined angle with respect to that optical axis of the projection system.
Also, in Japanese Patent Laying-Open No. 2004-157560 (2004), for example, there is already disclosed a reflection-type image forming optical system, for projecting an image on the image display element(s) onto the screen (i.e., the tracing surface), enlargedly, with using a plural number of reflection mirrors.